This invention relates generally to bar code reading systems and more specifically to a dual bar code reading system for a data cartridge storage system.
Machine readable codes, such as bar codes, are well-known in the art and are used in various applications to allow a machine (e.g., a bar code reader) to read the code. Perhaps the most common application of such machine readable codes (e.g., bar codes) is their use in inventory control situations where it is desired to identify and keep track of the movement of objects and things.
Regardless of the application in which it is used, a typical bar code reading device will include an optical system suitable for detecting the bar codes on the objects. Depending on the particular application, the bar code reader may be provided with an illumination system suitable for illuminating the bar code to allow the same to be detected.
Bar code reading devices may be used in data storage systems to read bar code labels placed on data cartridges. Data encoded on the bar code labels are used by the data storage system to keep track of (i.e., inventory) the locations and identities of the various data cartridges contained in the data storage system.
In general, data storage systems, of which there are many different types, are used for storing data cartridges at known locations and for retrieving those data cartridges from those locations so that data may be written to or read from those data cartridges. Such data storage systems are often referred to as xe2x80x9cjuke boxxe2x80x9d data storage systems, particularly if they can accommodate a large number of individual data cartridges.
A typical data storage system may include one or more different types of cartridge receiving devices for holding the various data cartridges. For example, one type of cartridge receiving device may comprise a cartridge storage rack or xe2x80x9cmagazinexe2x80x9d while another type of cartridge receiving device may comprise a cartridge read/write device. The cartridge storage racks or magazines serve to provide storage locations for the data cartridges and are commonly arranged so that they form one or more vertical stacks. The cartridge read/write device may be located adjacent the cartridge stack, although the cartridge read/write device may be positioned at any convenient location. The data storage system may also be provided with a cartridge access device for accessing the various data cartridges contained in the cartridge receiving devices and a positioning system for moving the cartridge access device among the various cartridge receiving devices contained in the data storage system.
Typically, if certain data contained on a particular data cartridge is desired, the host computer system will issue commands to a control system associated with the data storage system. In response to those commands, the control system will actuate the positioning system to move the cartridge access device along the cartridge storage racks or magazines until the cartridge access device is positioned adjacent the desired data cartridge. As mentioned above, a bar code reading device may assist the control system in determining when the cartridge access device has been positioned adjacent the desired data cartridge. In other words, the bar code reading device reads the bar code label positioned on the data cartridge to verify that the data cartridge is the desired data cartridge. If not, the cartridge access device may be moved to another data cartridge. Once the desired data cartridge has been located, the cartridge access device may remove the desired cartridge from the cartridge storage rack and carry it to the cartridge read/write device. The cartridge access device may then insert the selected data cartridge into the cartridge read/write device so that the host computer may thereafter read data from or write data to the selected data cartridge. After the read/write operation is complete, the cartridge access device may remove the data cartridge from the cartridge read/write device and return it to its appropriate location in the cartridge storage rack.
Although many types of data storage devices and media (e.g., magnetic disk or tape, optical disk, etc.) may be used in data storage systems of the type just described, a commonly used data storage device comprises a digital linear tape (xe2x80x9cDLTxe2x80x9d) cartridge. A bar code label is often placed on each cartridge in order to distinguish and identify the various DLT cartridges. In one application, the bar code label contains six characters.
Recently, DLT cartridges are being replaced in data storage systems with linear tape open (xe2x80x9cLTOxe2x80x9d) cartridges. The newer LTO cartridges are designed to be compatible with DLT systems so that most existing DLT systems can be converted for use with the new LTO cartridges. Unfortunately, however, the newer LTO cartridges are not entirely compatible with DLT cartridges. For example, as was the case with the DLT cartridges, the LTO cartridges are provided with bar code labels so that the various LTO cartridges contained within the data storage system may be identified and inventoried. However, the bar code labels utilized with the LTO cartridges comprise eight characters and are physically longer than the 6-character bar code labels previously used to identify the DLT cartridges. Since the LTO bar code labels are longer than the bar code labels previously used with DLT cartridges, most bar code readers utilized in DLT systems cannot read the longer bar code labels associated with the LTO cartridges. That is, the bar code readers contained in the DLT systems do not have fields of view that are large enough to read the longer LTO labels in their entireties.
While it is possible to modify or replace DLT type bar code readers with bar code readers suitable for reading the longer LTO labels, such modification or replacement of the bar code readers is expensive and difficult to implement. Another solution to the problem would be to use xe2x80x9ccondensedxe2x80x9d or xe2x80x9chigh densityxe2x80x9d bar code labels with the newer LTO cartridges. Such condensed or high density labels would allow the eight characters to be represented on a shorter label. Unfortunately, however, the resolution of the bar code readers utilized in DLT systems may not be sufficient to resolve the condensed or high density characters (e.g., bars) contained on such shorter labels. Consequently, it may still be necessary to modify or replace the current bar code readers, an expensive and undesirable circumstance.
Accordingly, a need remains for a bar code reading system capable of reading the entirety of a larger bar code label even though a portion of the bar code label is located outside the field of view of the bar code reading device. Ideally, the bar code reading system would be compatible with and require no physical modifications to the bar code reading device. In addition, the bar code reading system should be inexpensive, simple to use and not require a significant amount of time to implement.
A bar code reading system may comprise a first bar code label and a second bar code label. The first bar code label is positioned on an object at a first location and in a first orientation. The second bar code label is positioned on the object at a second location and in a second orientation. The first and second bar code labels each have indicia thereon that are representative of a label data set. A bar code reader positionable next to the object has a limited field of view such that the bar code reader reads only first and second portions of the first and second bar code labels. The bar code reader produces first and second data sets representative of the first and second portions. A data processing system operatively associated with the bar code reader combines the first and second data sets to produce a combined data set that is representative of the label data set.
Also disclosed is a method for reading bar code labels with limited-view bar code reading apparatus that comprises the steps of: Positioning a first bar code label on an object at a first location and in a first orientation, the first bar code label having indicia thereon that are representative of a label data set; positioning a second bar code label on the object at a second location and in a second orientation, the second bar code label having indicia thereon that are representative of the same label data set; positioning the bar code reader apparatus next to the object; operating the bar code reading apparatus to read first and second portions of the first and second bar code labels and to produce first and second data sets that are representative of the first and second portions; and combining the first and second data sets to produce a combined data set that is representative of the label data set.